Multistep synthesis of a novel copper complex with potential for Alzheimer's disease diagnosis.

Positron emission tomography (PET) imaging of Aß plaques, is recognized as a tool for the diagnosis of Alzheimer's disease. As a contribution to the development of new strategies for early diagnosis of the disease, using PET medical imaging technique, a new copper complex, the [Cu(TE1PA-ONO)]+ was synthesized in ten steps. The key step of our strategy is the coupling of a monopicolinate-N-alkylated cyclam-based ligand with a moiety capable of recognizing Aß plaques via a successful and challenging Buchwald-Hartwig coupling reaction. To our knowledge, it is the first time that such a strategy is used to functionalize polyazamacrocyclic derivatives. The thermodynamic stability constants determined in MeOH/H2O solvent indicate that the attachment of this moiety does not weaken the chelating properties of TE1PA-ONO ligand in relation to parent HTE1PA. The novel complex described here is able to recognize amyloid plaques in brain sections from Alzheimer's disease patients and shows low toxicity to human neuronal cells.

Synthesis and preliminary anticancer evaluation of new triazole bisphosphonate-based isoprenoid biosynthesis inhibitors.

The synthesis of a new set of triazole bisphosphonates 8a-d and 9a-d presenting an alkyl or phenyl substituent at the C-4 or C-5 position of the triazole ring is described. These compounds have been evaluated for their antiproliferative activity against MIA PaCa-2 (pancreas), MDA-MB-231 (breast) and A549 (lung) human tumor cell lines. 4-hexyl- and 4-octyltriazole bisphosphonates 8b-c both displayed remarkable antiproliferative activities with IC50 values in the micromolar range (0.75-2.4 µM) and were approximately 4 to 12-fold more potent than zoledronate. Moreover, compound 8b inhibits geranylgeranyl pyrophosphate biosynthesis in MIA PaCa-2 cells which ultimately led to tumor cells death.

Formation of 1-Hydroxymethylene-1,1-bisphosphinates through the Addition of a Silylated Phosphonite on Various Trivalent Derivatives.

An easily handled one-pot synthetic procedure was previously developed for the synthesis of bisphosphinates starting from acyl chlorides. Herein, other trivalent derivatives as acid anhydrides and activated esters were tested to form various bisphosphinates. This modulation of the reactivity can be controlled according to the nature of the acid derivative for the use of sensitive and functionalized substrates.

A convenient synthetic route towards H-bisphosphinates.

A practical generalisable procedure to synthesize hydroxymethylene H-bisphosphinates has been optimised. Unlike previous reports, numerous alkyl (including an alendronate bisphosphinate analogue) or (hetero)aryl compounds were rapidly obtained in satisfactory to excellent yields. A side product could have been identified as a phosphino-phosphonate isomer and plausible mechanistic pathways are proposed here. Moreover to check the literature data, a pKa value study was also performed.

Bifunctional Tripeptide with a Phosphonic Acid as a Brønsted Acid for Michael Addition: Mechanistic Insights.

Enamine catalysis is a widespread activation mode in the field of organocatalysis and is often encountered in bifunctional organocatalysts. We previously described H-Pro-Pro-pAla-OMe as a bifunctional catalyst for Michael addition between aldehydes and aromatic nitroalkenes. Considering that opposite selectivities were observed when compared to H-Pro-Pro-Glu-NH2 , an analogue described by Wennemers, the activation mode of H-Pro-Pro-pAla-OMe was investigated through kinetic, linear effect studies, NMR analyses, and structural modifications. It appeared that only one bifunctional catalyst was involved in the catalytic cycle, by activating aldehyde through an (E)-enamine and nitroalkene through an acidic interaction. A restrained tripeptide structure was optimal in terms of distance and rigidity for better selectivities and fast reaction rates. Transition-state modeling unveiled the particular selectivity of this phosphonopeptide.

Towards potential nanoparticle contrast agents: Synthesis of new functionalized PEG bisphosphonates.

The use of nanotechnologies for biomedical applications took a real development during these last years. To allow an effective targeting for biomedical imaging applications, the adsorption of plasmatic proteins on the surface of nanoparticles must be prevented to reduce the hepatic capture and increase the plasmatic time life. In biologic media, metal oxide nanoparticles are not stable and must be coated by biocompatible organic ligands. The use of phosphonate ligands to modify the nanoparticle surface drew a lot of attention in the last years for the design of highly functional hybrid materials. Here, we report a methodology to synthesize bisphosphonates having functionalized PEG side chains with different lengths. The key step is a procedure developed in our laboratory to introduce the bisphosphonate from acyl chloride and tris(trimethylsilyl)phosphite in one step.

Iron thiolate complexes: efficient catalysts for coupling alkenyl halides with alkyl Grignard reagents.

Ironing out the kinks: Efficient new catalytic systems based on iron thiolates are described for the iron-catalyzed cross-coupling of alkyl Grignard reagents with alkenyl halides. The reaction is highly chemo- and stereoselective. With this new procedure, the use of N-methylpyrrolidone as a co-solvent is no longer required.

Manganese-catalyzed cross-coupling reaction between aryl Grignard reagents and alkenyl halides.

Aryl Grignard reagents react stereospecifically with alkenyl halides in the presence of manganese chloride (10%) to afford good yields of cross-coupling products.

Stereoselective preparation of dienol phosphates from alpha,beta-ethylenic aldehydes.

The first stereoselective method of preparation of (E)-dienol phosphates from alpha,beta-ethylenic aldehydes is described. The key point is the stereoselective enolization of conjugated alkenals by potassium tert-butoxide in the presence of N-methylpyrrolidinone (NMP).

Efficient preparation of terminal conjugated dienes by coupling of dienol phosphates with grignard reagents under iron catalysis.

An efficient new route to prepare stereoselectively terminal conjugated dienes by coupling Grignard reagents and dienol phosphates in the presence of Fe(acac)3 is described. The synthetic utility of this new iron-catalyzed procedure is illustrated by the synthesis of the pheromone of Diparopsis castanea according to a very expeditious strategy.